MongoDB adapter: queries on _uid don't pass collation, causing COLLSCAN instead of IXSCAN

### 👟 Reproduction steps After migrating from Appwrite 1.9 to 1.9.5 with a MongoDB-backed instance, I noticed severe slowdowns on stats/executions writes. Investigation showed that indexes on internal collections (e.g. _uid) are created WITH a collation ({ locale: 'en', strength: 1 }), but queries against those same fields are issued WITHOUT a matching collation. Because MongoDB requires a query's collation to match an index's collation to use it, this causes every _uid lookup to fall back to a full COLLSCAN instead of using the existing index — even though the index exists and is correctly built. Steps to reproduce: 1. Fresh MongoDB-backed Appwrite instance, self-hosted via docker compose 2. Let normal usage occur (function executions, stats writes) 3. Run explain() on a _uid-filtered find() against any internal collection (e.g. _stats or _executions) — winningPlan.stage returns COLLSCAN, totalKeysExamined: 0, despite a unique _uid index existing with collation set. ### 👍 Expected behavior Expected: query should use the existing _uid index (IXSCAN). Actual: full collection scan every time, causing major CPU/performance issues even at idle (MongoDB container consistently >100% CPU with no active traffic). ### 👎 Actual Behavior Ran `docker compose exec appwrite migrate` to attempt a fix — migration completed successfully but did not resolve the issue. ### 🎲 Appwrite version Appwrite Cloud ### 💻 Operating system Linux ### 🧱 Your Environment Environment: - Appwrite 1.9.5, self-hosted (Windows + Docker Desktop + WSL2) - MongoDB 8.2.5 - Mongosh 2.8.1 ### 👀 Have you spent some time to check if this issue has been raised before? - [x] I checked and didn't find similar issue ### 🏢 Have you read the Code of Conduct? - [x] I have read the [Code of Conduct](https://github.com/appwrite/.github/blob/main/CODE_OF_CONDUCT.md)